There are many bags with waist belts, and there are many bags with shoulder straps, and there are many bags that have both waist belts and shoulder straps, with either removable or fixedly attached shoulder straps or waist belts, and many bags with loops for holding removable waist belts. These bags may allow carrying what is needed, but they do not always keep the wearer comfortable or the contents easily accessible or usable while the bag is being worn by the person. These bags may even keep the load primarily on the shoulder, with use of the shoulder strap. If the size or weight of the load is large, these bags can be quite uncomfortable. Also, the bags may become unwieldy, making walking difficult due to the weight felt on shoulder or—without shoulder strap—on the hips, and there may be awkwardness in the case of a bag hanging below the waist of a bag hitting the lower back and/or leg area of the wearer. Sagging bags may also make access to or use of contents difficult, as the contents move to the lower center point of the bag in the case of a bag with one large or with a plethora of large compartments or pockets. If it is attempted to bypass this gathering of contents by utilizing small interior or exterior compartment or pocket, then it may be difficult to access the individual content items, and the bag may yet sag.
A hard bag may solve some of the organizational or access problems, but a hard bag presents problems of discomfort and inaccessibility. A hard case or bag is difficult to wear close to the human body because, while the case or bag may be rigidly geometric, the human body is flexible and unevenly curved, making carrying heavy if the weight is on shoulder, or impossible to bend or move if the weight is against back or hip.